“UCB is the intersection of playfulness and industriousness,” said Pierson, a member of the group DERRICK Comedy, between songs. “It’s a supportive community full of really talented people that just by existing and being the hard-working, talented people they are, will challenge you to be better. The principles that they teach – like the Game of the Scene, which means focusing on and expanding what is funny about the sketch or the improvised scene that you’re doing – can be applied across all media. And in life.”

A café, gallery/performance lounge, retail space, video-production offices and 14 classrooms comprise the two-story industrial structure near the intersection of Sunset Boulevard and Western Avenue. By 6 p.m. VIPs and UCB students had poured into every room. Outside, a standby line of fans in black UCB hoodies and beanies snaked up the main entrance ramp, hoping for a coveted spot in one of two ASSSSCAT shows inaugurating the 85-capacity theater.

Throughout the reception and ASSSSCAT twofer, UCB house teams transformed the complex’s second floor classrooms into a series of miniature theme parties, each offering their own complimentary beverages. Attendees strolled from Royal Bermuda Whiskey Club’s “Satanic Mass” to DunkTank’s “Shrine to Meryl Streep” to Team Nephew’s “Uncle Warren’s Wake” to the Dragons’ “The Floor Is Lava,” sipping Team Tut’s “Studio 54” drink “White Line Sangria” or “1994 Slumber Party” cocktail of choice “Long Island Iced Tea Stolen from Mom and Dad’s Liquor Cabinet” along the way. The in-joke highlight: Team Landlord’s “UCB Franklin” room, a deliberately shabby black box featuring “a blue cooler full of Bud Light, Sierra Nevada, Coke, Diet Coke, Sprite and water,” a play on UCB's existing space on Franklin Avenue.

“It’s gigantic and confusing and loud and it’s awesome,” enthused UCB regular Betsy Sodaro of the atmosphere, taking a break from the “Frat Party!” room’s Jungle Juice and raucous beer pong match. “It feels like a college. Downstairs feels like a student union. This is such an exciting thing for everyone who is involved and wants to be involved and who don’t know yet that they will be involved one day. UCB has done everything for me career-wise and life-wise. It is my life.”

Back downstairs, Poehler, Besser, Roberts and Walsh opened the 8:30 ASSSSCAT with a welcome speech thanking the behind-the-scenes members who not only helped search five years for the perfect new digs, but dedicated an additional three years to procuring and remodeling the former methadone clinic. Fans who couldn’t get seats stood along the walls, crouched on the stairs and sat at the lip of the stage, with comediansDavid Wain, Nick Kroll and Scott Auckerman among those lining the floor.

“We didn’t have a vision; we didn’t have a dream of having a theater,” Besser explained of UCB’s original New York location. “What made it so great is the theater had to come about. The people performing and doing good work made it necessary for us to have a theater. That community working so well made it necessary to have a second theater in L.A.”

At 10 p.m., a one-off “5419 Show” showcased 90 different solo and group acts performing one minute each — for a grand total of approximately 5419 seconds of material — in honor of the venue’s numerical street address. Faux-chat hosts Ronna and Beverly were the first to the stage, with rapid-fire highlights including UCB veterans Bangarang! and the Birthday Boys; standups Kumail Nanjiani, Emily Heller, Anthony Jeselnik and Moshe Kasher; the Walsh Brothers’ “Naked Yeti” character baring it all; Ben Garant as Reno 911!’s Deputy Travis Junior; Bob Odenkirk reading fake hatemail from TMZ; and Wain wowing with a card trick while Natasha Leggero coaxed her tutu-clad pup Mayor Cutie to jump through a pink hoop.

As the show swelled to two hours and 15 minutes, announcer and UCB L.A. artistic director Mike Still got louder and more opinionated, at one point observing “There’s been a lot of white people rapping tonight.” By midnight the stage itself was strewn with sawdust, post-its, kitty litter, a chewed-up hot dog, a slice of pizza and the remnants of a pumpkin. As Still rightly noted, “You guys got real sad when that pizza fell!”

Eventually, spiritually-minded Seth Morris creation Bob Ducca purified the new space by burning sage. When the sparklers tucked among the bundle set off the fire alarm just as Kroll’s set began, Poehler appeared a final time, giggling apologetically while entreating a rapid exit from the crowded, smoky theater. (Rumor had it that the chaos nixed two final acts, including Aziz Ansari.) While the public dutifully tramped outside, partygoers followed thumping music down twisting back halls to the gallery, where flashing lights and deafening surroundings obscured the hazard strobes and warning sirens, ensuring the wall-to-wall dance celebration continued deep into the night.

Correction: UCB originally provided the wrong name for the group DunkTank. We regret the error.